Communicating with a RDBMS Using SQL Database SQL> SELECT loc 2 FROM dept; SQL> SELECT loc 2 FROM dept; SQL statement is entered Statement is sent to database LOC NEW YORK DALLAS CHICAGO BOSTON LOC NEW YORK DALLAS CHICAGO BOSTON Data is displayed

SQL Statements SELECT INSERTUPDATEDELETECREATEALTERDROPRENAMETRUNCATECOMMITROLLBACKSAVEPOINTGRANTREVOKE Data Retrieval Language (DRL) Data Retrieval Language (DRL) Data Manipulation Language (DML)‏ Data Definition Language (DDL)‏ Transaction Control Language (TCL)‏ Data Control Language (DCL)‏

Retrieval of data "…retrieve all employees in department 10" EMP EMPNO ENAME JOB... DEPTNO 7839KINGPRESIDENT BLAKEMANAGER CLARKMANAGER JONESMANAGER EMP EMPNO ENAME JOB... DEPTNO 7839KINGPRESIDENT CLARKMANAGER MILLERCLERK 10

Limiting Rows Selected Restrict the rows returned by using the WHERE clause. The WHERE clause follows the FROM clause. SELECT[DISTINCT] {*| column [alias],...} FROM table(, table,...)‏ [WHEREcondition(s)]; Optional

Using the WHERE Clause SQL> SELECT ename, job, deptno 2 FROM emp 3 WHERE job='CLERK'; ENAME JOB DEPTNO JAMES CLERK 30 SMITH CLERK 20 ADAMS CLERK 20 MILLER CLERK 10

Character Strings and Dates Character strings and date values are enclosed in single quotation marks. Character values are case sensitive and date values are format sensitive. The default date format is DD-MON-YY. SQL> SELECTename, job, deptno 2 FROM emp 3 WHEREename = 'JAMES'; SQL> SELECTename, job, deptno 2 FROM emp 3 WHEREename = 'JAMES';

Comparison Operators Operator = > >= < <= <> Meaning Equal to Greater than Greater than or equal to Less than Less than or equal to Not equal to

Using the Comparison Operators SQL> SELECT ename, sal, comm 2 FROM emp 3 WHERE sal<=comm; ENAME SAL COMM MARTIN

Other Comparison Operators Operator BETWEEN...AND... IN(list)‏ LIKE IS NULL Meaning Between two values (inclusive) Match any of a list of values Match a character pattern Is a null value

Using the BETWEEN Operator Use the BETWEEN operator to display rows based on a range of values. SQL> SELECTename, sal 2 FROM emp 3 WHEREsal BETWEEN 1000 AND 1500; Lower limit Higher limit ENAME SAL MARTIN 1250 TURNER 1500 WARD 1250 ADAMS 1100 MILLER 1300

Using the IN Operator Use the IN operator to test for values in a list. SQL> SELECTempno, ename, sal, mgr 2 FROM emp 3 WHEREmgr IN (7902, 7566, 7788); EMPNO ENAME SAL MGR FORD SMITH SCOTT ADAMS

Using the LIKE Operator Use the LIKE operator to perform wildcard searches of valid search string values. Search conditions can contain either literal characters or numbers. – % denotes zero or many characters. – _ denotes one character. SQL> SELECTename 2 FROM emp 3 WHEREename LIKE 'S%';

Using the LIKE Operator You can combine pattern-matching characters. You can use the ESCAPE identifier to search for "%" or "_". SQL> SELECTename 2 FROMemp 3 WHEREename LIKE '_A%'; ENAME MARTIN JAMES WARD

Using the IS NULL Operator Test for null values with the IS NULL operator. SQL> SELECT ename, mgr 2 FROM emp 3 WHERE mgr IS NULL; ENAME MGR KING

Logical Operators Operator AND OR NOT Meaning Returns TRUE if both component conditions are TRUE Returns TRUE if either component condition is TRUE Returns TRUE if the following condition is FALSE

Using the AND Operator AND requires both conditions to be TRUE. SQL> SELECT empno, ename, job, sal 2 FROM emp 3 WHERE sal>= AND job='CLERK'; EMPNO ENAME JOB SAL ADAMS CLERK MILLER CLERK 1300 NAME LIKE ‘%A%’

Using the OR Operator OR requires either condition to be TRUE. SQL> SELECT empno, ename, job, sal 2 FROM emp 3 WHERE sal>= OR job='CLERK'; EMPNO ENAME JOB SAL KING PRESIDENT BLAKE MANAGER CLARK MANAGER JONES MANAGER MARTIN SALESMAN JAMES CLERK rows selected.

Using the NOT Operator SQL> SELECT ename, job 2 FROM emp 3 WHERE job NOT IN ('CLERK','MANAGER','ANALYST'); ENAME JOB KING PRESIDENT MARTIN SALESMAN ALLEN SALESMAN TURNER SALESMAN WARD SALESMAN

Rules of Precedence Override rules of precedence by using parentheses. Order EvaluatedOperator 1All comparison operators 2NOT 3AND 4OR

Rules of Precedence ENAME JOB SAL KING PRESIDENT 5000 MARTIN SALESMAN 1250 ALLEN SALESMAN 1600 TURNER SALESMAN 1500 WARD SALESMAN 1250 ENAME JOB SAL KING PRESIDENT 5000 MARTIN SALESMAN 1250 ALLEN SALESMAN 1600 TURNER SALESMAN 1500 WARD SALESMAN 1250 SQL> SELECT ename, job, sal 2 FROM emp 3 WHERE job='SALESMAN' 4 OR job='PRESIDENT' 5 AND sal>1500;

Rules of Precedence ENAME JOB SAL KING PRESIDENT 5000 ALLEN SALESMAN 1600 ENAME JOB SAL KING PRESIDENT 5000 ALLEN SALESMAN 1600 Use parentheses to force priority. SQL> SELECT ename, job, sal 2 FROM emp 3 WHERE (job='SALESMAN' 4 OR job='PRESIDENT')‏ 5 AND sal>1500;

ORDER BY Clause Sort rows with the ORDER BY clause – ASC: ascending order, default – DESC: descending order The ORDER BY clause comes last in the SELECT statement. SQL> SELECT ename, job, deptno, hiredate 2 FROM emp 3 ORDER BY hiredate; ENAME JOB DEPTNO HIREDATE SMITH CLERK DEC-80 ALLEN SALESMAN FEB rows selected.

Sorting in Descending Order SQL> SELECT ename, job, deptno, hiredate 2 FROM emp 3 ORDER BY hiredate DESC; ENAME JOB DEPTNO HIREDATE ADAMS CLERK JAN-83 SCOTT ANALYST DEC-82 MILLER CLERK JAN-82 JAMES CLERK DEC-81 FORD ANALYST DEC-81 KING PRESIDENT NOV-81 MARTIN SALESMAN SEP rows selected.

Sorting by Column Alias SQL> SELECT empno, ename, sal*12 annsal 2 FROM emp 3 ORDER BY annsal; EMPNO ENAME ANNSAL SMITH JAMES ADAMS MARTIN WARD MILLER TURNER rows selected.

Sorting by Multiple Columns The order of ORDER BY list is the order of sort. You can sort by a column that is not in the SELECT list. SQL> SELECT ename, deptno, sal 2 FROM emp 3 ORDER BY deptno, sal DESC; ENAME DEPTNO SAL KING CLARK MILLER FORD rows selected.

Summary SELECT[DISTINCT] {*| column [alias],...} FROM table [WHEREcondition(s)] [ORDER BY{column, expr, alias} [ASC|DESC]];